Changes between Initial Version and Version 2 of Ticket #1533


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Timestamp:
Mar 25, 2007, 8:09:52 PM (17 years ago)
Author:
warmerdam
Comment:

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  • Ticket #1533 – Description

    initial v2  
    66The procedure used to retrieve the projection is using the Python GDAL bindings
    77as follows:
     8{{{
    89gd = gdal.Open("c:/rastername/w001001.adf")
    910gd.GetProjection()
     11}}}
    1012
    11 Note that the great majority of State Plane coordinate system use U.S. Survey
    12 feet rather than the international foot, and the difference is noticable.  The
    13 problem appears to arise when GDAL interprets the prj.adf file in the raster.
    14 Following is an example prj.adf for California Zone 6, which uses the U.S.
    15 survey foot.
     13Note that the great majority of State Plane coordinate system use U.S. Survey feet rather than the international foot, and the difference is noticable.  The problem appears to arise when GDAL interprets the prj.adf file in the raster.
    1614
     15Following is an example prj.adf for California Zone 6, which uses the U.S. survey foot.
     16
     17{{{
    1718Projection    STATEPLANE
    1819Fipszone      406
    … …  
    2425Yshift        0.0
    2526Parameters   
     27}}}
    2628
    27 ArcView reports the raster having the above prj.adf as being in the the U.S.
    28 Survey Foot.  It turns out that when Units are called out as FEET in the
    29 prj.adf file, this always means U.S. Survey Foot, not the international foot.
    30 When the international foot is the unit, the prj.adf file supplies the number
    31 of feet per meter e.g.
     29ArcView reports the raster having the above prj.adf as being in the the U.S. Survey Foot.  It turns out that when Units are called out as FEET in the prj.adf file, this always means U.S. Survey Foot, not the international foot.
    3230
     31When the international foot is the unit, the prj.adf file supplies the number of feet per meter e.g.
     32
     33{{{
    3334Units         3.280839895013123
     35}}}
    3436
    3537(That last number equals 1/0.3048 in case I typed it in wrong)
    3638
    37 I have done many experiments with ArcView to check this, creating custom
    38 projections, and changing the units between feet and international feet, and
    39 ArcView is consistent.  FEET always means the U.S. Survey foot in the prj.adf
    40 file.
     39I have done many experiments with ArcView to check this, creating custom projections, and changing the units between feet and international feet, and ArcView is consistent.  FEET always means the U.S. Survey foot in the prj.adf file.
    4140
    4241